Toxin genes from the bacteria xenorhabdus nematophilus and photorhabdus luminescens

ABSTRACT

The invention relates to the identification and isolation of polynucleotide molecules encoding a new class of protein insecticidal toxins which are produced by bacteria from the genera Xenorhabdus and Photorhabdus. The polynucleotide molecules may be incorporated into, for example, insect-specific viruses (including entomopox and nuclear polyhedrosis viruses), bacteria (including Gracilicutes, Firmicutes, Tenericutes and Mendosicutes), protozoa, yeast and plants for control of pest insects.

FIELD OF THE INVENTION

[0001] The present invention concerns the identification and isolation of a new class of protein toxins with specificity for insects, which are produced by bacteria from the genera Xenorhabdus and Photorhabdus. In addition, the present invention relates to the incorporation of genes encoding this class of toxin into, for example, insect-specific viruses (including entomopox and nuclear polyhedrosis viruses), bacteria (including Gracilicutes, Firmicutes, Tenericutes and Mendosicutes), yeast and plants for control of insect pests.

BACKGROUND OF THE INVENTION

[0002] Insect pathogenic nematodes of the families Steinernematidae and Heterorhabditidae are known to be symbiotically associated with bacteria of the genera Xenorhabdus and Photorhabdus respectively. It has been observed that these bacteria have the ability to kill a wide range of different insects without the aid of their nematode partners. The present inventors have isolated polynucleotide molecules encoding a new class of protein insecticidal toxins from Xenorhabdus nematophilus strain A24 and Photorhabdus luminescens strain V16/1.

DISCLOSURE OF THE INVENTION

[0003] In a first aspect, the present invention provides an isolated polynucleotide molecule encoding an insecticidal toxin, said polynucleotide molecule comprising a nucleotide sequence which substantially corresponds to the nucleotide sequence shown as SEQ ID NO: 1 or SEQ ID NO: 2.

[0004] In a second aspect, the present invention provides an isolated polynucleotide molecule encoding an insecticidal toxin, said polynucleotide molecule comprising a nucleotide sequence having at least 85%, more preferably at least 95%, sequence identity to the nucleotide sequence shown as SEQ ID NO: 2.

[0005] In a third aspect, the present invention provides an insecticidal toxin, in a substantially pure form, which toxin comprises an amino acid sequence having at least 95% sequence identity to that shown as SEQ ID NO: 3.

[0006] In a fourth aspect, the present invention provides an insecticidal toxin, in a substantially pure form, which toxin comprises an amino acid sequence having at least 85%, more preferably at least 95%, sequence identity to that shown as SEQ ID NO: 4.

[0007] Most preferably, the insecticidal toxin of the third or fourth aspect comprises an amino acid sequence substantially corresponding to that shown as SEQ ID NO: 3 or SEQ ID NO: 4 respectively.

[0008] In a fifth aspect the present invention provides a recombinant microorganism, the recombinant microorganism being characterised in that it is transformed with and expresses the polynucleotide molecule of the first or second aspects of the present invention.

[0009] The microorganisms which may be usefully transformed with the polynucleotide molecule of the first or second aspects of the present invention include bacteria, such as Escherichia, Gracilicutes, Firmicutes, Tenericutes and Mendosicutes; protozoa and yeast. The microorganism can be transformed by routine methods using expression vectors comprising the toxin-encoding polynucleotide molecule operably linked to a suitable inducible or constitutive promoter sequence.

[0010] In a sixth aspect, the present invention provides a method of producing an insecticidal toxin, said method comprising:

[0011] (i) culturing a microorganism according to the fourth aspect under conditions suitable for the expression of the toxin-encoding polynucleotide molecule, and

[0012] (ii) optionally recovering the expressed insecticidal toxin.

[0013] In a seventh aspect, the present invention provides a recombinant insect-specific virus, the recombinant insect-specific virus being characterised in that it includes within a non-essential region of its genome the polynucleotide molecule of the first or second aspects of the present invention operably linked to a suitable inducible or constitutive promoter sequence.

[0014] The recombinant insect-specific virus of the seventh aspect is preferably selected from entomopox and nuclear polyhedrosis viruses. The recombinant virus can be produced by routine methods such as homologous recombination.

[0015] In an eighth aspect, the present invention provides a method for killing pest insects, said method comprising applying to an area infested with said insects an effective amount of a recombinant microorganism according to the fourth aspect and/or a recombinant virus according to the seventh aspect, optionally in admixture with an acceptable agricultural carrier.

[0016] In a ninth aspect, the present invention provides a plant transformed with, and capable of expressing, the polynucleotide molecule of the first or second aspects of the present invention.

[0017] The plant according to the ninth aspect may be any plant of agricultural, arboricultural, horticultural or ornamental value that is susceptible to damage by feeding pest insects. However, preferably, the plant is selected from plants of agricultural value such as cereals (e.g.; wheat and barley), vegetable plants (e.g.; tomato and potato) and fruit trees (e.g., citrus trees and apples). Other preferred plants include tobacco and cotton.

[0018] The plant can be transformed by routine methods including Agrobacterium transformation and electroporation. Preferably, the toxin-encoding polynucleotide molecule is operably linked to a suitable inducible or constitutive promoter sequence. Particularly preferred promoter sequences include the cauliflower mosaic virus (CaMV 35 S) promoter element and promoter elements from the sub-clover stunt virus (SCSV).

[0019] The term “substantially corresponds” as used herein in relation to the nucleotide sequence is intended to encompass minor variations in the nucleotide sequence which due to degeneracy do not result in a change in the encoded protein. Further this term is intended to encompass other minor variations in the sequence which may be required to enhance expression in a particular system but in which the variations do not result in a decrease in biological activity of the encoded protein.

[0020] The term “substantially corresponding” as used herein in relation to the amino acid sequence is intended to encompass minor variations in the amino acid sequence which do not result in a decrease in biological activity of the insecticidal toxin. These variations may include conservative amino acid substitutions. The substitutions envisaged are:

[0021] G, A, V, I, L, M; D, E; N, Q; S, T; K, R, H; F, Y, W, H; and P, Nα-alkalamino acids.

[0022] The term “comprise”, “comprises” and “comprising” as used throughout the specification are intended to refer to the inclusion of a stated step, component or feature or group of steps, components or features with or without the inclusion of a further step, component or feature or group of steps, components or features.

[0023] The invention will hereinafter be further described by way of reference to the following, non-limiting example and accompanying figures.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

[0024]FIG. 1: Nucleotide sequence of the protein coding (sense) strand of the X. nematophilus DNA insert of clone toxb4. The translation initiation codon (ATG) at nucleotide position 17-19 and the translation termination codon (TAA) at nucleotide position 1121-1123 are indicated by shaded boxes. Locations of oligonucleotide sequences used for sequencing primer design are indicated by arrows and a primer name (TOX F1, TOX R3 etc.). Arrows directed left-to-right, positioned above the sequence indicate sense-strand primers, arrows directed right-to-left, positioned below the sequence indicate anti-sense primers.

[0025]FIG. 2: Deduced sequence of the 368 amino acid toxb4 protein from X. nematophilus strain A24, derived by conceptual translation of the long open reading frame commencing at nucleotide position 17 and ending at nucleotide position 1120 of the toxb4 gene sequence (FIG. 1).

[0026]FIG. 3: Restriction map of P. luminescens V16/1 toxin gene clone showing location of putative toxin protein coding region (solid black box) and direction of transcription (arrow). RI=EcoRI, RV=EcoRV, H=Hind III, S=Sma I. Toxin production from clones containing selected restriction fragments is indicated above the restriction map (+, toxin activity; −, no toxin activity).

[0027]FIG. 4: Nucleotide sequence of the protein coding (sense) strand of the P. luminescens Hind III/Sma I DNA fragment. Translation initiation (ATG) and termination (TGA) codons are indicated by shaded boxes. Locations of oligonucleotide sequences used for sequencing primer design are indicated by arrows and a primer name as described in the brief description of FIG. 1. Restriction enzyme sites used for sub-cloning and identification of sequences necessary for toxin activity are underlined and labelled on the figure.

[0028]FIG. 5: Deduced sequence of the 335 amino acid PlV16tox1 protein from P. luminescens strain V16/1, derived by conceptual translation of the long open reading frame commencing at nucleotide position 172 and ending at nucleotide position 1179 of the Hind III/Sma I restriction enzyme fragment (FIG. 4).

[0029]FIG. 6: Alignment of the nucleotide sequences encompassing the protein open reading frames of the X. nematophilus strain A24toxb4 gene and the P. luminescens strain V16/1 PlV16tox1 gene using the Gap program of the GCG computer software package. The X. nematophilus sequence is the upper line and the P. luminescens sequence is the lower line.

[0030]FIG. 7: Alignment of the deduced protein sequences of the extended open reading frames encoding the X. nematophilus A24 toxb4 protein and the P. luminescens strain V16/1 PlV16tox1 protein using the Gap program of the GCG computer software package. The X. nematophilus sequence is the upper line and the P. luminescens sequence is the lower line.

[0031]FIG. 8: Provides a scheme for expressing and isoltating X. nematophilus A24toxb4 protein and P. luminescens V16/7 PlV16tox1 protein using the IMPACT™ system. The toxin protein is represented schematically as a solid black bar with the first (Met) and last (Ile) amino acids indicated.

EXAMPLE 1

[0032] Isolation and Characterisation of Toxin genes from Xenorhabdus nematophilus A24 and Photorhabdus luminescens

[0033] Construction of Recombinant Bacterial DNA Libraries

[0034] High molecular weight genomic DNA was isolated from Xenorhabdus nematophilus strain A24 using the method of Marmur (1961) and from Photorhabdus luminescens strain V16/1 by the method of Scott et al. (1981). The genomic DNA was partially digested with the restriction enzyme Sau 3AI to generate fragments of DNA in the size range 30 to 50 kilobase pairs and dephosphorylated by incubation with the enzyme calf intestinal alkaline phosphatase. The cosmid cloning vector “Supercos” (Stratagene) was linearised by digestion with the restriction enzyme Bam HI and ligated to the partially digested bacterial DNA at a vector:genomic DNA ratio of 1:3 according to standard procedures (Maniatis et al., 1982). The ligated DNA was packaged in vitro using Gigapack II XL Packaging Extract according to manufacturer's instructions (Stratagene). The packaged DNA was transfected into the Escherichia coli strain NM554 (F⁻, recA, araD139, Δ(ara, leu) 7696, Δlac Y74, galU−, galK−, hsr, hsm⁺, strA, mcrA[−], mcrA[−]). Transfected bacteria were plated onto Luria Bertani (LB) agar medium containing 150 μg ml⁻¹ ampicillin, to select for bacteria containing recombinant cosmid clones.

[0035] Isolation of an Insect Toxin Gene from Xenorhabdus nematophilus Strain A24 by Functional Screening

[0036] Cultures of bacteria harbouring individual cosmid clones were grown overnight at 28° C. in LB broth containing 150 μg ml⁻¹ ampicillin. The bacterial cultures were treated for 15 minutes with 2 mg ml⁻¹ lysozyme to create cell-free lysates. Five microlitre aliquots of these lysates were injected into the haemocoel of three Galleria mellonella fourth instar larvae. Two clones with insecticidal activity were identified. Control lysates prepared by lysozyme treatment of E. coli NM554 cells containing non-recombinant Supercos vector possessed no toxin activity in the Galleria bioassay.

[0037] Characterisation of Toxin Producing Clones

[0038] Cosmid DNA from toxin-expressing clones was isolated-using a standard alkaline lysis procedure (Maniatis et al., 1982). Isolated DNA was analysed by restriction enzyme digestion and agarose gel electrophoresis (Maniatis et al., 1982). Both cosmid clones appeared to contain the same region of approximately 34.6 kb of X. nematophilus genomic DNA. One clone, designated cos149 was chosen for further analysis.

[0039] A 7.4 kb Bam HI fragment from cos149 was ligated into the plasmid vector pGEM7Z(f)+(Promega Biotec) and transformed into the E. coli strain DH5a (F⁻, F8odlac ZΔ M15, recA1, endA1, gyrA96, thi-1, hsdR17 [rK⁻ mK₊] supE44, relA1, deoR, Δ[lacZYA-argF] U169) using electroporation at 25 mF, 200 and 2.5 kV in a 0.2 cm cuvette in a Bio-Rad Gene Pulser. The resultant sub-clone was designated N8pGEM. Lysates prepared from E. coli cells containing the N8pGEM clone contained toxin as determined by the Galleria haemolymph injection bioassay.

[0040] A set of unidirectional deletion clones was prepared from N8pGEM according to the method of Henikoff (1984) using the Erase-a-base kit (Promega Biotec) and digestion with the enzymes Cla I and Sph I. Deleted DNA was recircularised by ligation with T4 DNA ligase and transformed into E. coli strain DH5α by electroporation as described above. Deletion sub-clones of varying sizes were identified and tested for toxin production using the Galleria bioassay. The smallest clone that retained toxin expression (designated tox 1) contained 1.5 kb of X. nematophilus DNA.

[0041] Plasmid DNA from the tox 1 clone was isolated, digested with the restriction enzymes Sac I and Hind III and directionally deleted with the Erase-a-base kit. A set of deleted clones was identified and tested for toxin production. The smallest clone retaining toxin activity (designated toxb4) contained 1.2 kb of X. nematophilus DNA. The toxb4 clone was sequenced on both strands with a combination of vector and gene-specific sequencing primers and ABI Prism™ di-deoxy dye-terminator sequencing mix (Applied Biosystems). Plasmid DNA was prepared by a standard alkaline lysis procedure (Maniatis et al., 1982), the double-stranded DNA was sequenced by a thermal cycle sequencing protocol, and sequencing reactions were analysed on an automated DNA sequencer (Applied Biosystems Model 377) according to manufacturer's instructions.

[0042] The toxb4 clone contained an insert 1205 bp in length (FIG. 1) which encoded a protein open reading frame of 368 amino acid residues (FIG. 2). Searches of the non-redundant Genbank nucleotide and protein databases were done for the toxb4 nucleotide and deduced protein sequences using the blastn, fasta and blastp, programs for DNA and protein sequences. No statistically significant similarity was detected between the X. nematophilus sequences and sequences present in the databases.

[0043] Isolation of a toxb4 Homologue from Photorhabdus luminescens Strain V16/1

[0044] The genomic DNA cosmid library prepared from P. luminescens strain V16/1 was screened by nucleic acid hybridisation using the toxb4 gene as a hybridisation probe. Two hundred clones were grown overnight at 37° C. on LB agar plates containing 150 μg ml⁻¹ ampicillin and the resultant bacterial clones were transferred to nylon membrane discs (Colony/Plaque Screen™, NEN DuPont) according to the manufacturer's protocol. Colonies were lysed in situ on the membranes by treatment with 0.5 N NaOH and neutralised with 1.0M Tris-Cl, pH 7.5, and the cosmid DNA was immobilised on the membranes by air drying. Filters were pre-hybridised in a solution consisting of 5×SSPE, 0.2% w/v skim-milk powder, 0.5% w/v SDS and 0.2% mg/ml denatured salmon sperm DNA at 68° C. for 3 hours. A hybridisation probe was prepared by radiolabelling approximately 100 ng of isolated toxb4 DNA with 50 μCi α-³²P-dATP by random-primed synthesis using the Gigaprime DNA labelling kit (GPK-1, Bresatec). Filters were incubated with the toxb4 probe in 5×SSPE, 0.2% w/v skim-milk powder, 0.5% w/v SDS and 0.2% mg/ml denatured salmon sperm DNA at 68° C. overnight. Filters were rinsed briefly in 2×SSC, and washed once for 15 min at room temperature in 2×SSC, 0.1% w/v SDS, once at 68° C. for 30 min in 0.5×SSC, 0.2% SDS. After a final rinse in 0.5×SSC filters were autoradiographed for 24 hours at −80° C. Three clones that hybridised with the toxb4 probe were identified. Cultures were grown for each clone and cell lysates were assayed for toxicity using the Galleria bioassay. Two clones, designated cos154 and cos160 showed toxin expression. Cosmid DNA was isolated from cos154 and cos160 and analysed by restriction enzyme digestion and Southern blot hybridisation. An 8.5 kb Not I restriction enzyme fragment that hybridised to the toxb4 probe was isolated from clone cos160 and sub-cloned into the Not I site of the plasmid vector pBC (KS)+(Stratagene). Further restriction enzyme mapping and bioassay resulted in identification of a 2.4 kb Eco RI fragment that contained all the sequences necessary for production of active toxin.

[0045] Characterisation of the P. luminescens Strain V16/1 Toxin Gene

[0046] Three additional sub-clones of the 2.4 kb Eco RI fragment were constructed and tested for toxin production (FIG. 3). A 1.65 kb Hind III/Eco RI fragment, a 1.39 kb Hind III/Sma I fragment and a 1.44 kb Eco RV/Eco RI fragment were each ligated into the plasmid vector pBluescript II (KS)+(Stratagene) and the ligated DNA was transformed into E. coli strain DH10B™ (Stratagene) (F⁻ mcrA Δ(mrr-hsdRMS-mcrBC) F8odlacZΔM15 ΔlacX74 deoR recA1 araD139 Δ(ara, leu)7697 galU galKl⁻ rpsL nupG). Cell lysates were prepared from cultures containing each of these sub-clones and bioassayed by haemocoel injection into Galleria larvae. Cultures containing the 1.65 kb Hind III/Eco RI fragment and the 1.39 kb Hind III/Sma I fragment expressed active toxin but cultures containing the 1.44 kb Eco RV/Eco RI fragment were inactive in the bioassay (FIG. 3). Thus, sequences located 5′ to the Eco RV site of the P. luminescens V16/1 Hind III/Eco RI fragment are required for toxin expression from the plasmid pBluescript II (KS)+, whereas sequences 3′ to the Sma I site are dispensable. The toxin gene is designated PlV16tox1 and the toxin protein encoded by this gene is designated PlV16tox1. A strategy was developed for sequencing the 1.39 kb Hind III/Sma I P. luminescens DNA fragment based on internal restriction enzyme sites and custom-synthesised oligonucleotide sequencing primers. The complete sequence of the 1.39 kb Hind III/Sma I fragment was determined on both strands (FIG. 4). Analysis of this DNA sequence identified a single long open reading frame 335 amino acid residues in length (FIG. 5).

[0047] Comparison of the Toxin Gene and Protein Sequences from X. nematophilus and P. luminescens

[0048] The DNA sequences corresponding to the deduced toxin protein open reading frames were compared for the two bacterial species using the ‘Gap’ program of the GCG software package. The two gene sequences are 83% identical in the coding region (FIG. 6) but show no significant similarity in the sequences immediately 5′ and 3′ of the extended open reading frame. The toxin protein sequences were likewise compared with the ‘Gap’ program and found to be 75% identical to each other and 86% similar if physico-chemically conservative amino acid differences were taken into consideration (FIG. 7). The existence of two extended insertion/deletion variants between the two proteins identifies amino acids that are not essential for toxic activity against Galleria melonella.

EXAMPLE 2

[0049] Distribution of the Toxin Gene from X. nematophilus A24

[0050] Genomic DNA was prepared from the type strain for each of four identified Xenorhabdus species, an additional unclassified Xenorhabdus species and six Photorhabdus luminescens strains selected to include at least one member of each of the major genetic groups identified by analysis of 16S ribosomal RNA genes (Brunel et al., 1997). The DNA was digested with restriction enzymes, fractionated by agarose gel electrophoresis and transferred to nylon membranes by the Southern blot method (Maniatis et al., 1982) The filters were hybridised with a probe prepared from the X. nematophilus A24 toxb4 gene. Hybridisation conditions were selected that would allow sequences with an average identity of approximately 65% to be detected. The results are shown in Table 1. TABLE 1 Bacterial species Strain Toxin gene^(†) Xenorhabdus nematophilus A24 + Xenorhabdus nematophilus AN6 + Xenorhabdus poinarii G6 − Xenorhabdus beddingii Q58 − Xenorhabdus bovienii T28 − Xenorhabdus sp. K77 − Photorhabdus luminescens Hb − Photorhabdus luminescens Hm − Photorhabdus luminescens C1 − Photorhabdus luminescens V16 + Photorhabdus luminescens C8406 + Photorhabdus luminescens K81 +

[0051] Clearly, homologues of the toxin gene from X. nematophilus A24 is present in some species of the genus Xenorhabdus, and some, but not all isolates of Photorhabdus luminescens.

EXAMPLE 3

[0052] Activity of Toxin Genes Cloned into Plasmid Vectors and Transformed into E. coli

[0053] Active toxin protein was expressed when the A24 toxb4 clone or V16 tox1 genes were inserted into general plasmid vectors of the type pGEM (Promega Biotec) or pBluescript (Stratagene) and the recombinant plasmids transformed into E. coli. More specifically, the X. nematophilus toxin A24 toxb4gene was cloned into the plasmid pGEM7z and the P. luminescens V16 tox1 gene was cloned into pBluescript SK.

[0054] Preparation of Cell Extract

[0055] A culture of E. coli cells transformed with either a recombinant plasmid containing a toxin gene or a non-recombinant parent plasmid was grown overnight at 37° C. in nutrient broth. Lysozyme was added to the culture to a final concentration of 1 mg/ml and the mixture left at room temperature for 30 minutes to lyse the cells. The cleared lysate was used directly for bioassay.

[0056] Bioassay

[0057] Extracts were bioassayed using the intrahaemocoel injection assay. Ten microlitres of E. coli cell lysate were injected into the abdominal region of a Galleria mellonella larvae through an intersegmental membrane. Bioassays were done on lo larvae for each extract and injected larvae were held at 22° C. Mortality was recorded daily. Results are shown in Table 2. TABLE 2 Percentage mortality Toxin source Day 1 Day 2 Day 3 Day 4 Day 5 PlV16tox1 0 20 40 90 100 pBluescript SK (control) 0 10 10 10 20 A24toxb4 10 10 10 100 100 pGEM7z (control) 0 0 10 20 20

[0058] Extracts prepared from E. coli cells transformed with recombinant plasmids containing the toxin gene from either X. nematophilus A24 or P luminescens strain V16/1 kill G. mellonella larvae and caused complete mortality of injected individuals five days after injection. Extracts prepared from cells containing only the plasmid vectors pBluescript SK or pGEM7z did not kill the larvae.

[0059] Effect of Temperature on Toxicity

[0060] Extracts were prepared from E. coli cells transformed either with cloned toxin genes or the empty plasmid vector controls and injected into G. mellonella larvae as described previously. The injected larvae were maintained at either 20° C. or 25° C. Results are shown in Table 3. TABLE 3 Percentage mortality Day Day Day Day Day Day Toxin source Temp 1 2 3 4 5 6 PlV16tox1 20° C. 0 10 25 60 90 100 PlV16tox1 25° C. 0 0 100 100 100 100 pBluescript SK 20° C. 0 0 0 0 0 0 pBluescript SK 25° C. 0 5 10 10 15 15 A24toxb4 20° C. 5 30 35 65 95 100 A24toxb4 25° C. 60 75 100 100 100 100 pGEM7z 20° C. 0 5 5 5 5 5 pGEM7z 25° C. 0 5 5 5 5 5

[0061] Extracts prepared from cells containing either the cloned toxin gene from X. nematophilus A24 or the P. luminescens V16 toxin gene killed all larvae within three days for larvae held at 25° C. or by six days for larvae maintained at 20° C. following injection. Control extracts prepared from cells containing only the cloning vectors pBluescript or pGEM7z did not cause significant larval mortality.

EXAMPLE 4

[0062] Toxin Activity Against Different Insect Species

[0063] (1) Helicoverpa armigera (Lepidoptera:Noctuidae)

[0064] Bioassay

[0065] Extracts were bioassayed using the intrahaemocoel injection assay. Ten microlitres of E. coli cell lysate were injected into the abdominal region of fourth instar Helicoverpa armigera larvae through an intersegmental membrane. Bioassays were done on 24 larvae for each extract and injected animals were held at 27° C. Mortality was recorded daily. Results are shown in Table 4. TABLE 4 Percentage mortality Toxin source Day 1 Day 2 Day 3 Day 4 PlV16tox1 38 71 87 91 pBluescript SK 4 4 8 8 A24toxb4 50 87 91 91 pGEM7z 0 0 0 0

[0066] Extracts prepared from E. coli cells transformed with recombinant plasmids containing the toxin gene from either X. nematophilus A24 or P luminescens strain V16/1 caused significant mortality to injected larvae within 24 hours after injection. All larvae died by 4 days following the injection, with the exception of a small number of “escapees” that resulted from leakage of injected material upon removal of the injection needle. Extracts prepared from cells containing only the plasmid vectors pBluescript SK or pGEM7z had no significant effect on H. armigera larvae.

[0067] (2) Plodia interpunctella (Lepidoptera:)

[0068] Bioassay

[0069] Extracts were bioassayed using the intrahaemocoel injection assay. Five microlitres of E. coli cell lysate were injected into the abdominal region of a final instar Plodia interpunctella larva through an intersegmental membrane. Bioassays were done on 20 wandering-stage larvae for each extract and injected animals were held at 26° C. Mortality was recorded daily. Results are shown in Table 5. TABLE 5 Percentage mortality Toxin source Day 1 Day 2 Day 3 PlV16tox1 20 90 100 pBluescript SK 0 0 0 A24toxb4 75 95 100 pGEM7z 0 5 5

[0070] Extracts prepared from E. coli cells transformed with recombinant plasmids containing the toxin gene from either X. nematophilus A24 or P luminescens strain V16/1 caused significant mortality to injected larvae within 24 hours after injection. All larvae had died within 3 days. Extracts prepared from cells containing only the plasmid vectors pBluescript SK or pGEM7z had no significant effect on survival of P. interpunctella larvae.

[0071] (3) Lucilia cuprina (Diptera: Calliphoridae) Adults

[0072] Bioassay

[0073] Extracts were bioassayed using the intrahaemocoel injection assay. Five microlitres of E. coli cell lysate were injected into the abdomen of a 3 day old Lucilia cuprina female fly through an intersegmental membrane. Bioassays were done on 20 flies for each extract and injected animals were held at 25° C. Mortality was recorded daily. Results are shown in Table 6. TABLE 6 Percentage mortality Toxin source Day 1 Day 2 Day 3 Day 4 PlV16tox1 55 65 85 100 pBluescript SK 20 25 25 25 A24toxb4 55 75 85 100 pGEM7z 30 60 65 65

[0074] Extracts prepared from E. coli cells transformed with recombinant plasmids containing the toxin gene from either X. nematophilus A24 or P luminescens strain V16/1 caused significant mortality to injected flies within 24 hours of injection. All flies died by 4 days after injection. Extracts prepared from cells containing only the plasmid vectors pBluescript SK or pGEM7z also caused significant mortality to the L. cuprina flies in the first 48 hours following injection. After this control mortality stabilised, there was no further deaths for the remainder of the test period. Additional experiments with saline injections showed that the early mortality in the control group resulted from physical damage to the flies as a result of the injection process.

[0075] (4) Lucilia cuprina (Diptera:Calliphoridae) Larvae

[0076] Bioassay

[0077] Extracts were bioassayed using the intrahaemocoel injection assay. Five microlitres of E. coli cell lysate were injected into the abdominal cavity of wandering-stage final instar Lucilia cuprina larvae through an intersegmental membrane. Bioassays were done on 20 larvae for each extract and injected animals were held at 25° C. Mortality was recorded daily. Results are shown in Table 7. TABLE 7 Percentage mortality Toxin source Day 1 Day 2 Day 3 Day 4 PlV16tox1 35 45 75 80 pBluescript SK 25 30 30 30 A24toxb4 10 35 90 95 pGEM7z 15 20 20 25

[0078] Extracts prepared from E. coli cells transformed with recombinant plasmids containing the toxin gene from either X. nematophilus A24 or P luminescens strain V16/1 caused significant mortality to injected larvae within 48 hours of injection. All larvae died by 4 days after injection, with the exception of a small number of “escapees” resulting from leakage at the time of needle withdrawal as previously described for H. armigera. As with the L. cuprina adults, extracts prepared from cells containing only the plasmid vectors pBluescript SK or pGEM7z caused significant mortality to the L. cuprina larvae in the first 48 hours following injection. After this, control mortality stabilised and there were no further deaths in this group of larvae for the remainder of the test period. As described above, experiments with saline injections showed that this early mortality in the control group resulted from physical damage to the larvae as a result of the injection process.

[0079] (5) Aphis gossypii (Hemiptera:Aphididae) Numphs Bioassay

[0080] Extracts were prepared from E. coli cells containing either the X. nematophilus toxin gene or the empty plasmid vector pGEM7z. The extracts were incorporated into a defined liquid diet at a concentration of 10% by volume and aphids were provided ad libitum access to diet for a period of five days. Results are shown in Table 8. TABLE 8 % Average Mortality Number of Treatment at day 5 Moults Control^(†) 10 1.9 pGEM7z extract 0 2 A24toxb4 extract 90 0.6 #extracts was included as a control for any potential effects of the lysozyme.

[0081] The X. nematophilus A24 toxin effectively blocked growth as seen from the reduction in the number of nymphal moults, and by five days had killed most of the larvae. Thus, the X. nematophilus A24 toxin was orally insecticidal to Aphis gossypii.

EXAMPLE 5

[0082] Expression and Purification of the Full-length Toxin Protein from X. nematophilus

[0083] Further characterisation of the properties of the toxins encoded by the cloned genes from X. nematophilus A24 and P. luminescens V16/1 required expression of the full-length protein in a format that allowed for affinity purification of the toxin. This was achieved by expressing the full-length toxin as a fusion protein in which the fusion partner was used for affinity selection, and the toxin domain was cleaved off chemically after the purification stage. A suitable expression and purification system is the IMPACT™ system (New England Biolabs) in which the toxin open reading frame is cloned at the 5′ end of a self-splicing intein coding sequence fused to a short DNA sequence encoding a chitin binding domain.

[0084] Recombinant plasmids containing both the X. nematophilus A24 toxin and the P. luminescens V16/1 toxin genes were prepared in the IMPACT™ vector pCYB3 (FIG. 8). Preparation of these constructs required the engineering of a unique restriction enzyme site at each end of the toxin open reading frame that enabled in-frame insertion of the toxin gene into the expression vector such that translation began at the Methionine initiation codon of the toxin protein and a cleavage site for protein splicing was placed immediately adjacent to the final residue of the toxin open reading frame. Expression of the fusion proteins in E. coli, preparation of bacterial cell extracts, affinity isolaton of the fusion proteins on chitin cellulose columns, on-column DTT-mediated cleavage of the fusion proteins and elution of the purified toxin proteins were all performed according to the manufacturer's instructions (IMPACT™ system manual, New England Biolabs)

[0085] For both toxin constructs a major protein product of the expected size (approximately 40 kDa) was detected by SDS polyacrylamide gel electrophoretic analysis of the column eluate. The preparations contained several other proteins but these comprised less than 10% of the total protein present in the samples as determined by Coomassie blue staining of the polyacrylamide gels. Approximately 750 μg of PlV16tox1 toxin and 1.5 mg of A24toxb4 toxin were isolated from one litre of E. coli broth cultures. Purified proteins were dialysed against phosphate-buffered saline and simultaneously concentrated by diafiltration to a final concentration of approximately 1 mg/ml on Millipore spin cartridges with a membrane nominal molecular weight cut-off of 10 kDa according to manufacturer's instructions (Millipore).

EXAMPLE 6

[0086] Biological Activity of Purified Toxin Proteins

[0087] Bioassay

[0088] The activity of the purified X. nematophilus and P. luminescens toxins were determined by intra-haemocoel injection bioassay on Galleria mellonella and Helicoverpa armigera larvae as described above. The toxin protein preparations were diluted in phosphate-buffered saline and 10 ml of protein solution was injected into each larva. Ten larvae were injected for each protein concentration and mortality was recorded at 12 hour intervals for six days after injection. Proteins were tested over a dose range from 1 nanogram (10⁻⁹ g) to 1 microgram (10⁻⁶ g) of protein per larva. An inert protein, E. coli maltose binding protein, was prepared in the IMPACT™ system, purified and concentrated according to the same methods used for the two toxin proteins. The purified maltose binding protein was used as a control for these experiments. The maltose binding protein did not cause larval mortality at any of the quantities tested. The results are shown in Tables 9 to 12. TABLE 9 Effect of purified PlV16 tox1 toxin on G. mellonella larvae Percentage Mortality Day Day Day Day Day Day Day Day Day Protein 2 2 3 3 4 4 5 5 6 Injected am pm am pm am pm am pm am   1 ng 0 0 0 0 0 0 0 0 0  10 ng 0 0 0 0 0 0 0 0 10  20 ng 0 10 10 20 20 20 20 30 30  100 ng 0 0 30 40 60 70 80 80 100  200 ng 0 0 44 56 56 78 100 100 100 1000 ng 20 20 60 60 100 100 100 100 100

[0089] TABLE 10 Effect of purified A24 toxb4 toxin on G. mellonella larvae Percentage Mortality Day Day Day Day Day Day Day Day Day Protein 2 2 3 3 4 4 5 5 6 Injected am pm am pm am pm am pm am   1 ng 0 0 0 0 0 0 0 0 0  10 ng 0 0 0 0 0 0 0 0 0  20 ng 0 0 10 20 20 40 60 70 80  100 ng 10 10 20 30 30 50 90 100 100  200 ng 0 0 0 0 50 70 70 90 100 1000 ng 0 0 0 10 60 80 100 100 100

[0090] TABLE 11 Effect of purified PlV16 tox1 toxin on H. armigera larvae Percentage Mortality Protein Day Day Day Day Day Day Day Day Injected 1/am 1/pm 2/am 2/pm 3/am 3/pm 4/am 4/pm   1 ng 0 0 0 0 0 0 0 0  10 ng 0 0 0 0 0 0 0 0  20 ng 0 10 10 10 10 10 10 10  100 ng 30 30 50 50 60 70 70 70  200 ng 0 0 80 80 80 80 80 80 1000 ng 22 67 100 100 100 100 100 100

[0091] TABLE 12 Effect of purified A24 toxb4 toxin on H. armigera larvae Percentage Mortality Protein Day Day Day Day Day Day Day Day Injected 1/am 1/pm 2/am 2/pm 3/am 3/pm 4/am 4/pm   1 ng 0 0 0 0 0 0 0 0  10 ng 0 30 50 70 90 90 90 90  20 ng 0 30 50 80 90 90 90 90  100 ng 0 20 80 100 100 100 100 100  200 ng 0 30 90 100 100 100 100 100 1000 ng 20 60 100 100 100 100 100 100

[0092] Both the X. nematophilus A24 toxin and the P. luminescens V16/1 toxin killed a high percentage of larvae after a single injection of at least 20 ng of toxin protein per larva. Mortality was dependent on toxin type and concentration. H. armigera was sensitive to small quantities of X. nematophilus A24 toxin with high mortality at 10-20 ng of toxin per larva, but was less sensitive to P. luminescens V16/1 toxin where significant mortality was observed only for quantities greater than 20 ng of protein per larva. A similar pattern of sensitivity was observed for G. mellonella larvae. The time taken to kill the larvae of either species was not strongly dependent on the time since toxin injection, although larger amounts of toxin killed more quickly. However, at all quantities greater than, or equal to 20 ng per larva the insects were effectively dead, because the H. armigera larvae ceased feeding and G. mellonella larvae were unable to spin cocoon silk.

[0093] Thus, the proteins encoded by the A24 toxb4 genes of X. nematophilus and the PlV16 tox1 gene of P. luminescens encode toxin proteins that are effective insecticides, especially of lepidopterous larvae including G. mellonella, H. armigera and P. interpunctella, when delivered into insect haemocoel.

EXAMPLE 7

[0094] Effect of Purified Toxin on Insect Cells in Culture

[0095] The purified X nematophilus A24 toxin and P. luminescens V16/1 toxin and the maltose binding protein control were each tested for their effects on the growth and viability of insect cells in tissue culture. A sample of 10⁴ cells in the appropriate culture medium was mixed with the test proteins at several different concentrations and seeded into the wells of a 96-well tissue culture plate. Cells were allowed to grow for 24 hours at 25° C. and cells were counted in a haemocytometer and assessed visually for cell lysis. The results are shown in Table 13.

[0096] For all cell lines, at all protein concentrations tested the maltose binding protein control had no effect on cell growth or viability. Neither of the toxin proteins had any significant effect on cell growth or viability for the Drosophila melanogaster Schneider 2 cell line. The X. nematophilus A24 toxin caused significant cell growth inhibition and cytotoxicity to the lepidopteran High-Five cell line at concentrations above 0.1 μg/ml. The P. luminescens V16 toxin caused slight growth inhibition only at the highest concentration tested of 1 μg/ml. The X. nematophilus A24 toxin caused significant cell growth inhibition and cytotoxicity to the lepidopteran Sf9 cell line at concentrations above 0.001 μg/ml, and the P. luminescens V16 toxin was toxic to this cell line at concentrations of 0.1 μg/ml and higher. Thus, toxins of this family exhibit growth inhibitory and cytotoxic activity against insect cells in tissue culture, especially cell lines of lepidopteran origin. Similar tests with a mouse hybridoma cell line demonstrated slight growth inhibition only by the X. nematophilus A24 toxin, and only at the highest concentration tested of 1 μg/ml. TABLE 13 Treatment Concentration Cell Line Toxin μg/ml Cells/well Schneider 2 PlV16tox1 0 4.1 × 10⁴ ″ 0.001 ND^(†) ″ 0.1 4.1 × 10⁴ ″ 1 4.6 × 10⁴ Schneider 2 A24toxb4 0 3.7 × 10⁴ ″ 0.001 ND ″ 0.1 3.6 × 10⁴ ″ 1 3.4 × 10⁴ High-Fives PlV16tox1 0 3.8 × 10⁴ ″ 0.001 ND ″ 0.1 3.9 × 10⁴ ″ 1 2.9 × 10⁴ High-Fives A24toxb4 0 8.2 × 10⁴ ″ 0.001 7.1 × 10⁴ ″ 0.1 2.5 × 10⁴ ″ 1 2.5 × 10⁴ Sf9 PlV16tox1 0 3.6 × 10⁴ ″ 0.001 4.3 × 10⁴ ″ 0.1   7 × 10³ ″ 1   6 × 10³ Sf9 A24toxb4 0 4.7 × 10⁴ ″ 0.001   1 × 10⁴ ″ 0.1   5 × 10³ ″ 1 6.5 × 10³

[0097] As will be appreciated by persons skilled in this field, the present invention provides a new class of toxins useful for genetically engineering a wide range of biological systems which will thus become more useful for control of pest insects detrimental to agricultural, aquatic and forest industries. This new class of toxin may be purified by one or more methods of protein purification well known in the art. Insecticidal fragments may be generated from the purified toxin using, for example, cleavage with trypsin or cyanogen bromide.

[0098] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

[0099] References

[0100] Brunel, B., Givaudin, A., Lanois, A., Akburst, R. J. and Boemare, N. (1997). Fast and accurate identification of Xenorhabdus and Photorhabdus species by restriction analysis of PCR-amplified 16S rRNA genes. Applied and Envirnomental Microbiology 63, 574-580.

[0101] Henikoff, S. (1984). Unidirectional digestion with exonuclease III creates targeted breakpoints for DNA sequencing, Gene 28, 351-359.

[0102] Innis, M. A., Gelford, D. H., Sminsky, J. J. and White, T. J. (1990). PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego.

[0103] Maniatis, T., Fritsch, E. F. and Sambrook, J. (1982). Molecular cloning: A laboratory manual. Cold spring Harbor Laboratory, Cold spring Harbor, N.Y.

[0104] Marmur J. (1961). A procedure for the isolation of deoxyribonucleic acid from micro organisms.

[0105] Scott, K. F., Rolfe, B. G. and Shine, J. (1981). Biological nitrogen fixation: primary structure of the Klebsiella pneumoniae nifH and nifD genes. J. Mol. Appl. Genet. 1, 71-81.

1 20 1 1107 DNA Xenorhabdus nematophilus 1 atggttatta aacccgtaac aactccgagt gtaatacaat taacgcctga tgatagagta 60 acgcctgatg ataaaggtga atatcaaccc gttgaaaagc aaatagcggg agatataata 120 cgtgtactag aattcaagca aacaaatgaa agtcatacag gattgtatgg aattgcatat 180 cgagctaaga aagtaataat agcatatgct ttagcggtaa gtggtattca taatgtctct 240 caacttccag aagactatta taaaaataag gataacacag gtagaattta tcaagaatac 300 atgtctaatc ttttatctgc actattgggt gagaatggtg atcaaatttc taaagatatg 360 gcaaatgatt ttacccagaa cgaactggag tttggaggtc aacgtcttaa aaatacctgg 420 gatattcctg atcttgagaa taaactattg gaagattatt cagatgaaga taaattatta 480 gcactatatt tctttgcttc acaagaactt ccaatggagg caaatcaaca atcaaatgca 540 gcaaattttt ttaaagtaat tgatttttta cttatcttat ctgctgtaac atcactggga 600 aaaaggattt tttcaaaaaa tttttacaat ggtctagaaa ctaaatcatt agagaattat 660 attgagagaa aaaaactttc taaacctttc tttcgaccac cgcagaagtt acctgatggc 720 agaacaggct acttggccgg tccaacaaaa gcgcctaaat tgccaacaac gtcttctaca 780 gcaacaacgt ctacagcagc ttcatctaat tggagagtta gtttgcaaaa acttagagat 840 aacccatcca gaaatacatt tatgaaaatg gatgatgctg caaaacgaaa atatagttca 900 tttataaaag aggtacaaaa gggtaatgat ccacgtgcag cagcagcaag tattggtaca 960 aaaagcggca gtaacttcga aaaactgcaa ggtagagatt tatatagtat aagactaagc 1020 caagaacaca gggtaacatt ctccataaat aatactgacc aaataatgga gatccaaagt 1080 gttggaactc attaccaaaa tatataa 1107 2 1008 DNA Photorhabdus luminescens 2 atggttatac aattaacacc tgatgataga agtggatatc cacccgttga aaagcaaata 60 gcaggagata tagtacgtat actaaacttt aagcaaacag atgagggtca tacagcatca 120 tatggaattg aatatcgagc taagaaaata atattagctt acgctttggc tgtaagtggt 180 attcataatg tatctaaact tcctgatgac tattataaga ataaagagac tgctgagaga 240 atttatcaag aatatatgtc taatctttca tctgcactat taggtgaaaa tggtgatcaa 300 atttctaaag atatggcaaa tggtttttat aagaatgaac tggattttga aggtcaatat 360 cctcaaaaca tttggaatgt tcctgagctt gaaaataaac cattgagtgc ttattcagat 420 gacgataaat tattagcact atattttttc tctgtacagg aaattccact ggaggaaaat 480 caacaatcaa atgccgcaag attttttaaa ttaattgatt tcttatttac cttatctgct 540 gtaacttcac tgggaaggag gattttttca aaaaactttt acaatggatt agaggctaaa 600 tcattagaga attatattga gagaaaaaaa ctttctaaac ctttctttcg accaccgcag 660 agattacctg atggcagaat aggttatttg gctggaccaa cagaagcgcc taaatggaga 720 gtgagtttta aagaacttaa aaataacaaa tctaggaatg gattttctaa tatggaaggg 780 gctgcaaaac aaaagtatag ttcatttata aaagaggtac aaaagggtaa cgctccacag 840 acagcagcga aaagtattgg tacagccagt ggcagtaacc tggaaaaatt gccgaataat 900 ttatatagtg tgaggctaag ccaaaaagac agggtaacct ttactcaaaa tgatactgac 960 aatacaatga cggttcatag tgttggaact cattataaaa atatatga 1008 3 368 PRT Xenorhabdus nematophilus 3 Met Val Ile Lys Pro Val Thr Thr Pro Ser Val Ile Gln Leu Thr Pro 1 5 10 15 Asp Asp Arg Val Thr Pro Asp Asp Lys Gly Glu Tyr Gln Pro Val Glu 20 25 30 Lys Gln Ile Ala Gly Asp Ile Ile Arg Val Leu Glu Phe Lys Gln Thr 35 40 45 Asn Glu Ser His Thr Gly Leu Tyr Gly Ile Ala Tyr Arg Ala Lys Lys 50 55 60 Val Ile Ile Ala Tyr Ala Leu Ala Val Ser Gly Ile His Asn Val Ser 65 70 75 80 Gln Leu Pro Glu Asp Tyr Tyr Lys Asn Lys Asp Asn Thr Gly Arg Ile 85 90 95 Tyr Gln Glu Tyr Met Ser Asn Leu Leu Ser Ala Leu Leu Gly Glu Asn 100 105 110 Gly Asp Gln Ile Ser Lys Asp Met Ala Asn Asp Phe Thr Gln Asn Glu 115 120 125 Leu Glu Phe Gly Gly Gln Arg Leu Lys Asn Thr Trp Asp Ile Pro Asp 130 135 140 Leu Glu Asn Lys Leu Leu Glu Asp Tyr Ser Asp Glu Asp Lys Leu Leu 145 150 155 160 Ala Leu Tyr Phe Phe Ala Ser Gln Glu Leu Pro Met Glu Ala Asn Gln 165 170 175 Gln Ser Asn Ala Ala Asn Phe Phe Lys Val Ile Asp Phe Leu Leu Ile 180 185 190 Leu Ser Ala Val Thr Ser Leu Gly Lys Arg Ile Phe Ser Lys Asn Phe 195 200 205 Tyr Asn Gly Leu Glu Thr Lys Ser Leu Glu Asn Tyr Ile Glu Arg Lys 210 215 220 Lys Leu Ser Lys Pro Phe Phe Arg Pro Pro Gln Lys Leu Pro Asp Gly 225 230 235 240 Arg Thr Gly Tyr Leu Ala Gly Pro Thr Lys Ala Pro Lys Leu Pro Thr 245 250 255 Thr Ser Ser Thr Ala Thr Thr Ser Thr Ala Ala Ser Ser Asn Trp Arg 260 265 270 Val Ser Leu Gln Lys Leu Arg Asp Asn Pro Ser Arg Asn Thr Phe Met 275 280 285 Lys Met Asp Asp Ala Ala Lys Arg Lys Tyr Ser Ser Phe Ile Lys Glu 290 295 300 Val Gln Lys Gly Asn Asp Pro Arg Ala Ala Ala Ala Ser Ile Gly Thr 305 310 315 320 Lys Ser Gly Ser Asn Phe Glu Lys Leu Gln Gly Arg Asp Leu Tyr Ser 325 330 335 Ile Arg Leu Ser Gln Glu His Arg Val Thr Phe Ser Ile Asn Asn Thr 340 345 350 Asp Gln Ile Met Glu Ile Gln Ser Val Gly Thr His Tyr Gln Asn Ile 355 360 365 4 335 PRT Photorhabdus luminescens 4 Met Val Ile Gln Leu Thr Pro Asp Asp Arg Ser Gly Tyr Pro Pro Val 1 5 10 15 Glu Lys Gln Ile Ala Gly Asp Ile Val Arg Ile Leu Asn Phe Lys Gln 20 25 30 Thr Asp Glu Gly His Thr Ala Ser Tyr Gly Ile Glu Tyr Arg Ala Lys 35 40 45 Lys Ile Ile Leu Ala Tyr Ala Leu Ala Val Ser Gly Ile His Asn Val 50 55 60 Ser Lys Leu Pro Asp Asp Tyr Tyr Lys Asn Lys Glu Thr Ala Glu Arg 65 70 75 80 Ile Tyr Gln Glu Tyr Met Ser Asn Leu Ser Ser Ala Leu Leu Gly Glu 85 90 95 Asn Gly Asp Gln Ile Ser Lys Asp Met Ala Asn Gly Phe Tyr Lys Asn 100 105 110 Glu Leu Asp Phe Glu Gly Gln Tyr Pro Gln Asn Ile Trp Asn Val Pro 115 120 125 Glu Leu Glu Asn Lys Pro Leu Ser Ala Tyr Ser Asp Asp Asp Lys Leu 130 135 140 Leu Ala Leu Tyr Phe Phe Ser Val Gln Glu Ile Pro Leu Glu Glu Asn 145 150 155 160 Gln Gln Ser Asn Ala Ala Arg Phe Phe Lys Leu Ile Asp Phe Leu Phe 165 170 175 Thr Leu Ser Ala Val Thr Ser Leu Gly Arg Arg Ile Phe Ser Lys Asn 180 185 190 Phe Tyr Asn Gly Leu Glu Ala Lys Ser Leu Glu Asn Tyr Ile Glu Arg 195 200 205 Lys Lys Leu Ser Lys Pro Phe Phe Arg Pro Pro Gln Arg Leu Pro Asp 210 215 220 Gly Arg Ile Gly Tyr Leu Ala Gly Pro Thr Glu Ala Pro Lys Trp Arg 225 230 235 240 Val Ser Phe Lys Glu Leu Lys Asn Asn Lys Ser Arg Asn Gly Phe Ser 245 250 255 Asn Met Glu Gly Ala Ala Lys Gln Lys Tyr Ser Ser Phe Ile Lys Glu 260 265 270 Val Gln Lys Gly Asn Ala Pro Gln Thr Ala Ala Lys Ser Ile Gly Thr 275 280 285 Ala Ser Gly Ser Asn Leu Glu Lys Leu Pro Asn Asn Leu Tyr Ser Val 290 295 300 Arg Leu Ser Gln Lys Asp Arg Val Thr Phe Thr Gln Asn Asp Thr Asp 305 310 315 320 Asn Thr Met Thr Val His Ser Val Gly Thr His Tyr Lys Asn Ile 325 330 335 5 1205 DNA Xenorhabdus nematophilus 5 ataatgggaa agtacaatgg ttattaaacc cgtaacaact ccgagtgtaa tacaattaac 60 gcctgatgat agagtaacgc ctgatgataa aggtgaatat caacccgttg aaaagcaaat 120 agcgggagat ataatacgtg tactagaatt caagcaaaca aatgaaagtc atacaggatt 180 gtatggaatt gcatatcgag ctaagaaagt aataatagca tatgctttag cggtaagtgg 240 tattcataat gtctctcaac ttccagaaga ctattataaa aataaggata acacaggtag 300 aatttatcaa gaatacatgt ctaatctttt atctgcacta ttgggtgaga atggtgatca 360 aatttctaaa gatatggcaa atgattttac ccagaacgaa ctggagtttg gaggtcaacg 420 tcttaaaaat acctgggata ttcctgatct tgagaataaa ctattggaag attattcaga 480 tgaagataaa ttattagcac tatatttctt tgcttcacaa gaacttccaa tggaggcaaa 540 tcaacaatca aatgcagcaa atttttttaa agtaattgat tttttactta tcttatctgc 600 tgtaacatca ctgggaaaaa ggattttttc aaaaaatttt tacaatggtc tagaaactaa 660 atcattagag aattatattg agagaaaaaa actttctaaa cctttctttc gaccaccgca 720 gaagttacct gatggcagaa caggctactt ggccggtcca acaaaagcgc ctaaattgcc 780 aacaacgtct tctacagcaa caacgtctac agcagcttca tctaattgga gagttagttt 840 gcaaaaactt agagataacc catccagaaa tacatttatg aaaatggatg atgctgcaaa 900 acgaaaatat agttcattta taaaagaggt acaaaagggt aatgatccac gtgcagcagc 960 agcaagtatt ggtacaaaaa gcggcagtaa cttcgaaaaa ctgcaaggta gagatttata 1020 tagtataaga ctaagccaag aacacagggt aacattctcc ataaataata ctgaccaaat 1080 aatggagatc caaagtgttg gaactcatta ccaaaatata taacctgatt tatagtagtg 1140 ataagacgta agataaatat ggaaggttgt aattctattg cacttcctca gaggtgaccg 1200 ctcag 1205 6 1388 PRT Photorhabdus luminescens 6 Ala Ala Gly Cys Thr Thr Gly Cys Thr Ala Ala Thr Ala Ala Thr Thr 1 5 10 15 Cys Thr Thr Gly Cys Gly Thr Ala Ala Gly Thr Thr Ala Ala Thr Thr 20 25 30 Thr Thr Ala Cys Ala Thr Thr Gly Ala Ala Ala Thr Thr Ala Ala Cys 35 40 45 Gly Cys Thr Thr Ala Ala Ala Ala Ala Gly Cys Cys Ala Gly Gly Gly 50 55 60 Ala Ala Ala Ala Cys Thr Cys Thr Ala Thr Ala Thr Thr Thr Ala Ala 65 70 75 80 Ala Gly Thr Thr Gly Ala Ala Ala Thr Thr Thr Ala Thr Ala Thr Thr 85 90 95 Ala Gly Thr Ala Gly Cys Gly Ala Cys Ala Ala Ala Thr Thr Gly Cys 100 105 110 Gly Gly Ala Gly Thr Thr Thr Thr Cys Thr Gly Cys Cys Ala Gly Ala 115 120 125 Ala Ala Thr Thr Thr Cys Ala Thr Ala Gly Cys Thr Cys Ala Ala Ala 130 135 140 Thr Ala Ala Ala Cys Ala Thr Thr Ala Ala Cys Ala Thr Ala Ala Thr 145 150 155 160 Gly Gly Ala Gly Ala Ala Ala Thr Ala Thr Ala Ala Thr Gly Gly Thr 165 170 175 Thr Ala Thr Ala Cys Ala Ala Thr Thr Ala Ala Cys Ala Cys Cys Thr 180 185 190 Gly Ala Thr Gly Ala Thr Ala Gly Ala Ala Gly Thr Gly Gly Ala Thr 195 200 205 Ala Thr Cys Cys Ala Cys Cys Cys Gly Thr Thr Gly Ala Ala Ala Ala 210 215 220 Gly Cys Ala Ala Ala Thr Ala Gly Cys Ala Gly Gly Ala Gly Ala Thr 225 230 235 240 Ala Thr Ala Gly Thr Ala Cys Gly Thr Ala Thr Ala Cys Thr Ala Ala 245 250 255 Ala Cys Thr Thr Thr Ala Ala Gly Cys Ala Ala Ala Cys Ala Gly Ala 260 265 270 Thr Gly Ala Gly Gly Gly Thr Cys Ala Thr Ala Cys Ala Gly Cys Ala 275 280 285 Thr Cys Ala Thr Ala Thr Gly Gly Ala Ala Thr Thr Gly Ala Ala Thr 290 295 300 Ala Thr Cys Gly Ala Gly Cys Thr Ala Ala Gly Ala Ala Ala Ala Thr 305 310 315 320 Ala Ala Thr Ala Thr Thr Ala Gly Cys Thr Thr Ala Cys Gly Cys Thr 325 330 335 Thr Thr Gly Gly Cys Thr Gly Thr Ala Ala Gly Thr Gly Gly Thr Ala 340 345 350 Thr Thr Cys Ala Thr Ala Ala Thr Gly Thr Ala Thr Cys Thr Ala Ala 355 360 365 Ala Cys Thr Thr Cys Cys Thr Gly Ala Thr Gly Ala Cys Thr Ala Thr 370 375 380 Thr Ala Thr Ala Ala Gly Ala Ala Thr Ala Ala Ala Gly Ala Gly Ala 385 390 395 400 Cys Thr Gly Cys Thr Gly Ala Gly Ala Gly Ala Ala Thr Thr Thr Ala 405 410 415 Thr Cys Ala Ala Gly Ala Ala Thr Ala Thr Ala Thr Gly Thr Cys Thr 420 425 430 Ala Ala Thr Cys Thr Thr Thr Cys Ala Thr Cys Thr Gly Cys Ala Cys 435 440 445 Thr Ala Thr Thr Ala Gly Gly Thr Gly Ala Ala Ala Ala Thr Gly Gly 450 455 460 Thr Gly Ala Thr Cys Ala Ala Ala Thr Thr Thr Cys Thr Ala Ala Ala 465 470 475 480 Gly Ala Thr Ala Thr Gly Gly Cys Ala Ala Ala Thr Gly Gly Thr Thr 485 490 495 Thr Thr Thr Ala Thr Ala Ala Gly Ala Ala Thr Gly Ala Ala Cys Thr 500 505 510 Gly Gly Ala Thr Thr Thr Thr Gly Ala Ala Gly Gly Thr Cys Ala Ala 515 520 525 Thr Ala Thr Cys Cys Thr Cys Ala Ala Ala Ala Cys Ala Thr Thr Thr 530 535 540 Gly Gly Ala Ala Thr Gly Thr Thr Cys Cys Thr Gly Ala Gly Cys Thr 545 550 555 560 Thr Gly Ala Ala Ala Ala Thr Ala Ala Ala Cys Cys Ala Thr Thr Gly 565 570 575 Ala Gly Thr Gly Cys Thr Thr Ala Thr Thr Cys Ala Gly Ala Thr Gly 580 585 590 Ala Cys Gly Ala Thr Ala Ala Ala Thr Thr Ala Thr Thr Ala Gly Cys 595 600 605 Ala Cys Thr Ala Thr Ala Thr Thr Thr Thr Thr Thr Cys Thr Cys Thr 610 615 620 Gly Thr Ala Cys Ala Gly Gly Ala Ala Ala Thr Thr Cys Cys Ala Cys 625 630 635 640 Thr Gly Gly Ala Gly Gly Ala Ala Ala Ala Thr Cys Ala Ala Cys Ala 645 650 655 Ala Thr Cys Ala Ala Ala Thr Gly Cys Cys Gly Cys Ala Ala Gly Ala 660 665 670 Thr Thr Thr Thr Thr Thr Ala Ala Ala Thr Thr Ala Ala Thr Thr Gly 675 680 685 Ala Thr Thr Thr Cys Thr Thr Ala Thr Thr Thr Ala Cys Cys Thr Thr 690 695 700 Ala Thr Cys Thr Gly Cys Thr Gly Thr Ala Ala Cys Thr Thr Cys Ala 705 710 715 720 Cys Thr Gly Gly Gly Ala Ala Gly Gly Ala Gly Gly Ala Thr Thr Thr 725 730 735 Thr Thr Thr Cys Ala Ala Ala Ala Ala Ala Cys Thr Thr Thr Thr Ala 740 745 750 Cys Ala Ala Thr Gly Gly Ala Thr Thr Ala Gly Ala Gly Gly Cys Thr 755 760 765 Ala Ala Ala Thr Cys Ala Thr Thr Ala Gly Ala Gly Ala Ala Thr Thr 770 775 780 Ala Thr Ala Thr Thr Gly Ala Gly Ala Gly Ala Ala Ala Ala Ala Ala 785 790 795 800 Ala Cys Thr Thr Thr Cys Thr Ala Ala Ala Cys Cys Thr Thr Thr Cys 805 810 815 Thr Thr Thr Cys Gly Ala Cys Cys Ala Cys Cys Gly Cys Ala Gly Ala 820 825 830 Gly Ala Thr Thr Ala Cys Cys Thr Gly Ala Thr Gly Gly Cys Ala Gly 835 840 845 Ala Ala Thr Ala Gly Gly Thr Thr Ala Thr Thr Thr Gly Gly Cys Thr 850 855 860 Gly Gly Ala Cys Cys Ala Ala Cys Ala Gly Ala Ala Gly Cys Gly Cys 865 870 875 880 Cys Thr Ala Ala Ala Thr Gly Gly Ala Gly Ala Gly Thr Gly Ala Gly 885 890 895 Thr Thr Thr Thr Ala Ala Ala Gly Ala Ala Cys Thr Thr Ala Ala Ala 900 905 910 Ala Ala Thr Ala Ala Cys Ala Ala Ala Thr Cys Thr Ala Gly Gly Ala 915 920 925 Ala Thr Gly Gly Ala Thr Thr Thr Thr Cys Thr Ala Ala Thr Ala Thr 930 935 940 Gly Gly Ala Ala Gly Gly Gly Gly Cys Thr Gly Cys Ala Ala Ala Ala 945 950 955 960 Cys Ala Ala Ala Ala Gly Thr Ala Thr Ala Gly Thr Thr Cys Ala Thr 965 970 975 Thr Thr Ala Thr Ala Ala Ala Ala Gly Ala Gly Gly Thr Ala Cys Ala 980 985 990 Ala Ala Ala Gly Gly Gly Thr Ala Ala Cys Gly Cys Thr Cys Cys Ala 995 1000 1005 Cys Ala Gly Ala Cys Ala Gly Cys Ala Gly Cys Gly Ala Ala Ala 1010 1015 1020 Ala Gly Thr Ala Thr Thr Gly Gly Thr Ala Cys Ala Gly Cys Cys 1025 1030 1035 Ala Gly Thr Gly Gly Cys Ala Gly Thr Ala Ala Cys Cys Thr Gly 1040 1045 1050 Gly Ala Ala Ala Ala Ala Thr Thr Gly Cys Cys Gly Ala Ala Thr 1055 1060 1065 Ala Ala Thr Thr Thr Ala Thr Ala Thr Ala Gly Thr Gly Thr Gly 1070 1075 1080 Ala Gly Gly Cys Thr Ala Ala Gly Cys Cys Ala Ala Ala Ala Ala 1085 1090 1095 Gly Ala Cys Ala Gly Gly Gly Thr Ala Ala Cys Cys Thr Thr Thr 1100 1105 1110 Ala Cys Thr Cys Ala Ala Ala Ala Thr Gly Ala Thr Ala Cys Thr 1115 1120 1125 Gly Ala Cys Ala Ala Thr Ala Cys Ala Ala Thr Gly Ala Cys Gly 1130 1135 1140 Gly Thr Thr Cys Ala Thr Ala Gly Thr Gly Thr Thr Gly Gly Ala 1145 1150 1155 Ala Cys Thr Cys Ala Thr Thr Ala Thr Ala Ala Ala Ala Ala Thr 1160 1165 1170 Ala Thr Ala Thr Gly Ala Thr Gly Ala Gly Thr Ala Ala Thr Cys 1175 1180 1185 Thr Cys Thr Gly Ala Cys Thr Thr Cys Gly Ala Thr Thr Gly Ala 1190 1195 1200 Cys Ala Gly Ala Gly Cys Ala Thr Thr Thr Thr Thr Ala Ala Gly 1205 1210 1215 Cys Thr Cys Thr Cys Ala Thr Thr Thr Thr Cys Thr Cys Ala Ala 1220 1225 1230 Cys Gly Gly Gly Ala Gly Thr Cys Thr Cys Ala Thr Ala Ala Gly 1235 1240 1245 Gly Cys Gly Thr Thr Thr Thr Ala Cys Thr Thr Thr Thr Cys Ala 1250 1255 1260 Ala Gly Cys Cys Ala Cys Thr Ala Thr Gly Thr Gly Gly Thr Cys 1265 1270 1275 Thr Gly Thr Gly Ala Thr Ala Ala Thr Thr Gly Thr Ala Ala Ala 1280 1285 1290 Ala Cys Gly Cys Cys Thr Thr Cys Thr Thr Thr Thr Ala Gly Cys 1295 1300 1305 Cys Ala Ala Thr Ala Cys Ala Cys Thr Thr Thr Ala Cys Thr Ala 1310 1315 1320 Cys Cys Ala Ala Gly Ala Ala Ala Ala Thr Ala Thr Ala Thr Ala 1325 1330 1335 Cys Cys Cys Thr Ala Thr Gly Gly Ala Thr Thr Thr Cys Ala Ala 1340 1345 1350 Gly Ala Thr Gly Gly Ala Thr Cys Gly Cys Gly Gly Cys Gly Gly 1355 1360 1365 Cys Ala Ala Gly Gly Gly Ala Gly Cys Gly Ala Ala Thr Cys Cys 1370 1375 1380 Cys Cys Gly Gly Gly 1385 7 21 DNA Artificial Sequence Derived from X. nematophilus 7 ttagcggtaa gtggtattca t 21 8 21 DNA Artificial Sequence Derived from X. nematophilus 8 aggcaaatca acaatcaaat g 21 9 20 DNA Artificial Sequence Derived from X. nematophilus 9 gacgtaaact aacaactaaa 20 10 21 DNA Artificial Sequence Derived from X. nematophilus 10 tgatggcaga acaggctact t 21 11 21 DNA Artificial Sequence Derived from X. nematophilus 11 tctgcaacaa cgacatcttc t 21 12 20 DNA Artificial Sequence Derived from X. nematophilus 12 ggacacaaga accgaatcag 20 13 20 DNA Artificial Sequence Derived from P. luminescens 13 atggtgaatg tcggtttcgc 20 14 20 DNA Artificial Sequence Derived from P. luminescens 14 tgaactggat tttgaaggtc 20 15 20 DNA Artificial Sequence Derived from P. luminescens 15 gcagtagact tattcgtgag 20 16 20 DNA Artificial Sequence Derived from P. luminescens 16 ctttcgacca ccgcagagat 20 17 20 DNA Artificial Sequence Derived from P. luminescens 17 gtaaatccgc gaagacaacc 20 18 20 DNA Artificial Sequence Derived from P. luminescens 18 tgacggttca tagtgttgga 20 19 20 DNA Artificial Sequence Derived from P. luminescens 19 aggttgtgat acttggcagt 20 20 20 DNA Artificial Sequence Derived from P. luminescens 20 ccatcatttc acataaccga 20 

1. An isolated polynucleotide molecule encoding an insecticidal toxin, said polynucleotide molecule comprising a nucleotide sequence which substantially corresponds to the nucleotide sequence shown as SEQ ID NO: 1 or SEQ ID NO:
 2. 2. An isolated polynucleotide molecule according to claim 1, wherein said polynucleotide molecule comprises a nucleotide sequence which substantially corresponds to that shown as SEQ ID NO:
 1. 3. An isolated polynucleotide molecule according to claim 1, wherein said polynucleotide molecule comprises a nucleotide sequence which substantially corresponds to that shown as SEQ ID NO:
 2. 4. An isolated polynucleotide molecule encoding an insecticidal toxin said polynucleotide molecule comprising a nucleotide sequence having at least 85% sequence identity to the nucleotide sequence shown as SEQ ED NO:
 2. 5. An isolated polynucleotide molecule according to claim 4, wherein said polynucleotide molecule comprises a nucleotide sequence having at least 95% sequence identity to the nucleotide sequence shown as SEQ ID NO:
 2. 6. An insecticidal toxin, in a substantially pure form, which the toxin comprises an amino acid sequence having at least 95% sequence identity to that shown as SEQ ID NO:
 3. 7. An insecticidal toxin according to claim 6, wherein the toxin comprises an amino acid sequence substantially corresponding to that shown as SEQ ID NO:
 3. 8. An insecticidal toxin, in a substantially pure form, which the toxin comprises an amino acid sequence having at least 85% sequence identity to that shown as SEQ ID NO:
 4. 9. An insecticidal toxin according to claim 8, wherein the toxin comprises an amino acid sequence having at least 95% sequence identity to that shown as SEQ ID NO:
 4. 10. An insecticidal toxin according to claim 9, wherein the toxin comprises an amino acid sequence substantially corresponding to that shown as SEQ ID NO:
 4. 11. A recombinant microorganism, the microorganism being characterised in that it is transformed with and expresses a polynucleotide molecule according to any one of the claims 1 to
 5. 12. A recombinant microorganism according to claim 11, wherein the microorganism is selected from bacteria, protozoa and yeast.
 13. A method of producing an insecticidal toxin, said method comprising: (i) culturing a microorganism according to claim 11 or 12 under conditions suitable for the expression of the toxin-encoding polynucleotide molecule; and (ii) optionally recovering the expressed insecticidal toxin.
 14. A method for killing pest insects, said method comprising applying to an area infested with said insects an effective amount of a recombinant microorganism according to claim 11 or 12 optionally in admixture with an acceptable agricultural carrier.
 15. A recombinant insect-specific virus, the recombinant insect-specific virus being characterised in that it includes within a non-essential region of its genome a polynucleotide molecule according to any one of claim 1 to 5 operably linked to a suitable inducible or constitutive promoter sequence.
 16. A method for killing pest insects, said method comprising applying to an area infested with said insects an effective amount of a recombinant virus according to claim 15 optionally in admixture with an acceptable agricultural carrier.
 17. A plant transformed with, and capable of expressing, the polynucleotide molecule according to any one of claims 1 to
 5. 